Lady lavender blooms the first year from seed and re-blooms more than the other lavenders, but its blooms are very small.

All of my other lavenders (10 or so varieties) bloom big in May-June and if you harvest the first bloom they will give a second, smaller bloom in September.

There may be some of the Spanish lavenders with a longer bloom time, but I don't really count them as they have no scent and aren't "true lavenders" in my book.

I see you are in zone 6. Hardiness should be your first determining factor, if you want the lavender to come back year after year. Your English Lavender varieties are the best in regards to hardiness. Check those out for one that you like the characteristics of. Link included below.

FataMorgana

Here is a link that might be useful: Richters - Lavender varieties

Are there any varieties of lavender that will grow in zone 9 (north central florida)?

The French and Spanish lavenders are perfect for zones 8-10; in any zone lower than 8 they should be considered an annual.

The English and Intermediate lavenders are for zones 5-8.

You can generally "stretch" a plant to go one zone warmer; just don't expect the same performance. Going one zone cooler usually means the plant will be a goner once you get a cold winter unless to take major steps to protect it.

Having said that; Rosemary and Spanish lavender have both survived multiple winters here in zone 6b.